A digital rights management (DRM) license, associated with content protected by encryption, is a data structure generally containing:                an identifier for establishing the link between the license and the content to which it relates;        a cryptographic key enabling the content to be decrypted;        one or more conditions of use of the content.        
The conditions of use of the content may comprise a maximum number of uses of the content, a time window during which the content can be used, an authorized number of transfers of the content between different terminals, etc. In order to use content that is protected and associated with a DRM license using a terminal, a DRM client agent located in the terminal first checks whether the conditions of use are satisfied. If such is the case, the DRM client agent generally supplies the cryptographic key present in the license to a decryption module which then decrypts the content.
Moreover, there are parental control management applications. A parental control management application makes it possible to automatically restrict access to certain contents, in order to protect certain users from inappropriate contents. There are different types of parental control management applications. An application according to a first type is configured to apply the legislation in terms of parental control. An application according to a second type is managed by the parents in order to allow them to automatically restrict access to certain contents for their children. In this case, the application is parameterized by the parents who define parental criteria applicable to their children. The contents are characterized by information relating to their nature which may comprise, for example, levels in terms of violence, nudity and sex. When a user requests access to a given content, the parental control management application can provide the user with information concerning the nature of the content, in other words, concerning the levels of the content in terms of violence, nudity and sex. Then, if the parental criteria require the user to be of a certain age to access this content, the application can ask him or her to prove that he or she is old enough by prompting him or her either to input a confidential parental code, or to identify him/herself with a user account considered to be old enough, or to supply bank card details, or to provide identification data, etc. The parental control management application then determines whether the use of the content by the user concerned is authorized or not, depending on the proof provided.
The DRM systems make it possible to control the use of contents according to digital rights attached to these contents, whereas the parental control management applications make it possible to control the use of content on the basis of parental criteria. These two systems are quite distinct and not compatible. In particular, it is currently not possible to establish parental control simply on content protected and managed by a DRM license.
The document WO 2008/083163 describes a system (VPE—Viewing Policy Engine) for controlling access to encrypted contents stored on a media disk connected to a reader. When a user wants to read content stored on the media disk, the control system checks a set of conditions before authorizing or denying the reading of the content. These conditions may comprise a condition relating to the current date, said current date having to be later than a release date, a valid subscription condition, a condition relating to the number of times the content has been read, this number having to be less than a maximum number. Furthermore, if the content is prohibited to children whose age is below a given age limit, provision is made to request the input of a password. Thus, the document WO 2008/083163 provides, for access to encrypted content, for various access criteria (release date, subscription, etc.) to be checked and for a parental control operation to be performed. In the final analysis, this document proposes that one and the same control system simultaneously checks the content access criteria and performs a parental control operation with the user wanting to access the content. This system does, however, require the user to use the parental control module specific to the control system, which lacks flexibility.